Hard disk drives have been used in virtually all server computers built since the late 1980's, while the architecture of these computers has undergone sweeping changes. The use of server computers comprising a plurality of modular server blades is becoming more prevalent in systems previously utilizing unitary servers and server farms. A server blade is a circuit board populated with the components of a computer, such as a processor, memory (random access and read-only memory), a system bus, a hard disk drive and a network connection. Each blade is an independent system with its own memory, processor and network connection. Bladed servers stack numerous independent lower-end servers within a single cabinet. Due to their compact size, multiple blade servers can be placed in a single server rack or enclosure, allowing numerous systems to share electricity and HVAC resources.
Server blades are more cost-efficient, smaller and consume less power than traditional box-based servers. One source of their appeal lies in the fact that they may be inserted in a rack to conserve space. For example, one exemplary chassis manufactured by IBM can hold up to 14 processor blades. Six chassis can fit into a server rack, which could house up to 168 processors, or about double what a rack would house if stuffed with traditional “pizza box” servers.
Server blades have been designed for dedicated applications such as Web servers and caching servers that deliver Web pages to Internet browsers, SSL servers for encrypted communication, streaming servers for audio and video transmissions, running firewalls to keep intruders out of corporate networks, and housing DNS (domain name system) indexes that enable one computer to find another on the Internet.
Another advantage of server blades is their scalability. In subscriber service businesses, it is desirable to be able to grow server processing capacity to match increases in the subscriber base. For example, in an interactive television system it is desirable to increase processing in proportion to the number of subscribers (or the expected number of simultaneous subscriber sessions).
Implicit in the server blade model is the ability to retain some or all of the existing server blades when a new blade is added. The first server blades initially installed in a given rack may remain in service longer than a traditional unitary server. Therefore, a method of increasing the lifecycle of a server blade is advantageous. In addition, the use of “blade” servers will potentially increase the number of computers to be maintained in many facilities by orders of magnitude. For example, as noted above, more than one hundred blades can be installed in the space of a traditional server. The administrator of the blade server has to maintain the hardware and software in each blade. Because of the number of blades in a system can far exceed the number of traditional servers they replace, methods for improving the reliability of a server blade are also advantageous.
The main mechanical component (and likely point of failure) of a server blade is the hard disk drive (HDD), which provides the main non-volatile mass storage. Typical commercially available HDDs include a disk that spins at a speed of 7200 revolutions per minute. The disks rotate on bearings, which are prone to failure.
More reliable systems are desired.